/*-
 * ============LICENSE_START=======================================================
 * SDC
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 */
package org.openecomp.sdc.common.util;

import java.util.ArrayList;
import java.util.List;
import java.util.Spliterator;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

/**
 * Utility Class For Actions On Streams
 *
 * @author mshitrit
 */
public final class StreamUtils {

    private StreamUtils() {
        throw new UnsupportedOperationException();
    }

    /**
     * Breaks the stream when the predicate is not met.<br> Does not evaluate elements after the stream breaks.<br> This method evaluates the
     * stream.<br>
     *
     * @param stream
     * @param predicate
     * @return
     */
    public static <T> Stream<T> takeWhilePlusOneNoEval(Stream<T> stream, Predicate<T> predicate) {
        List<T> results = new ArrayList<>();
        Consumer<T> listAdder = results::add;
        stream.map(e -> {
            listAdder.accept(e);
            return e;
        }).filter(e -> !predicate.test(e)).findFirst();
        return results.stream();
    }

    public static <T> Stream<T> takeWhile(Stream<T> stream, Predicate<T> predicate) {
        return StreamSupport.stream(takeWhile(stream.spliterator(), predicate), false);
    }

    public static <T> Stream<T> takeWhilePlusOne(Stream<T> stream, Predicate<T> predicate) {
        return StreamSupport.stream(takeWhile(stream.spliterator(), new StopAfterFailPredicate<>(predicate)), false);
    }

    private static <T> Spliterator<T> takeWhile(Spliterator<T> splitr, Predicate<T> predicate) {
        return new MySplitIterator<>(splitr, predicate);
    }

    public static class MySplitIterator<T> extends AbstractSpliterator<T> implements Spliterator<T> {

        boolean stillGoing = true;
        private Spliterator<T> innerItr;
        private Predicate<T> innerPred;

        private MySplitIterator(Spliterator<T> splitItr, Predicate<T> pred) {
            super(splitItr.estimateSize(), 0);
            innerItr = splitItr;
            innerPred = pred;
        }

        @Override
        public boolean tryAdvance(Consumer<? super T> action) {
            boolean canAdvance = true;
            if (stillGoing) {
                stillGoing = innerItr.tryAdvance(createConsumerWrapper(action));
            } else {
                canAdvance = false;
            }
            return canAdvance;
        }

        private Consumer<? super T> createConsumerWrapper(Consumer<? super T> action) {
            return new Consumer<T>() {
                @Override
                public void accept(T t) {
                    stillGoing = innerPred.test(t);
                    if (stillGoing) {
                        action.accept(t);
                    }
                }
            };
        }
    }

    public static class StopAfterFailPredicate<T> implements Predicate<T> {

        boolean hasNotFailed;
        Predicate<T> innerPredicate;

        private StopAfterFailPredicate(Predicate<T> pred) {
            hasNotFailed = true;
            innerPredicate = pred;
        }

        ;

        @Override
        public boolean test(T t) {
            boolean isPassed;
            if (hasNotFailed) {
                isPassed = true;
                hasNotFailed = innerPredicate.test(t);
            } else {
                isPassed = false;
            }
            return isPassed;
        }
    }
}
